Wall ac to DC convertor

[Robotboy86]

So I am currently trying to make a convertor to take the wall's AC(North american, 110v) and convert it to about a 9v DC.

I had a 50v 4a rectifer laying around, so I am planning to use that. However I have a few quick questions.

1.  Its a radioshack 50v 4a full bridge recitifer, as such..  will it step the walls 120v down to 50v, or do I need to do that before hand?

2.  I am planning to use a transformer to step it down, just to wrap one with about 30 coils, and the second one with about 5 or so.  That should step it down towards near 9v, then I have a regulator IC.

3.  After it converts to DC, what do I use for ground?  do I just send that to the other side of the AC plug, or do I send it to the ground prong??

Thanks

dan

[pomprocker]

just buy one of these if you think that much of your time is worth more than 5 bucks:

http://www.sparkfun.com/commerce/product_info.php?products_id=298

[img width= height=]http://www.sparkfun.com/commerce/images/Main-Tools-9V-PS.jpg[/img]

[Robotboy86]

Hi jack ass.

Please note this forum is for learning.

Not for smart ass answers.

Now, please go hurt yourself.

[Robotboy86]

alright i NEARLY feel bad about the above answer So

I am building several things into one power supply.  To not only power one device at around 9v, but also a few others at 5v and 12v's.  So knowing how to build it, has a point.

[pomprocker]

no seriously, its a time versus money issue.

make yourself a bench-top atx power supply 



http://letsmakerobots.com/node/1355

[Robotboy86]

No seriously, its a time vs learning question.

I'm not buying a solution, or anything else. I am looking to get the above mentioned questions answered.

If your not able to answer them, bugger off.

[Robotboy86]

I do appreciate the link though

[Spoil9]

Robotboy,
I know how it feels to ask a question that everyone else knows the answer to except you.
1.  The bridge rectifier will NOT step down the voltage. The 50v is the max it will take before burning it's self up and shorting out. So you will need to use a step-down transformer before it.

2. I would not recommend building your own transformer though. They are really cheap to buy. I know the wal-wart is too, but for learning purposes I would still buy a transformer. Radio Shack sells them cheap.

3.  After the step down transformer, and the bridge rectifier, you will have your + and - output's. The link below should bring you to a picture of a simple diagram. If not, then do a Google search for Bridge Rectifier and look at any of the images that pop up.

http://opencircuitdesign.com/xcircuit/tutorial/giffiles/bridge.gif

You can see in this one that they have a couple Caps going across the + and - leads. This is to help smooth out any ripple that may have worked it's way through the rectifier. The IC is not perfect and you will have ripple on the DC side. How much I do not know, but it depends on what your powering with this if you really need to worry about it or not.
If you really need a solid 9VDC, then consider using a 9V regulator after the Caps.
Good luck.
- Bill

[dsheller]

Making your own transformer isn't a very good solution, there is more to worry about than just the correct turn ratio. The link pomprocker provided you is an excellent solution for DC supplies, however, no combination of those voltages will provide you with exactly 9V... you could potentially use -5 and +5 and throw that through a 9V regulator. Also, everything Spoil9 said is correct, and the link he gave you for a rectification circuit is a good one to book mark if you haven't already memorized it.

[Admin]

Robotboy86, people (such as the forum experts) won't want to help you if your negative . . .